Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Gear systems have proven to be one of the most effective machines in achieving mechanical advantage. The effectiveness of gear systems is such that almost all moving equipment that we see today has a gear system integrated. According to the functionality of the machine, the utilized gear system can vary. The amount of torque, speed, and direction of movement depends upon the gear's design. More specifically, the components and the arrangement of a gear system differ from one to another. The main concept behind a gear system is the transfer of rotational force from one gear or device to another.
Gear systems have a series of advantages and disadvantages. The advantages include the ability to transmit the exact velocity ratio, the ability to transmit large power, the ability to be used for small center distances of shafts, having high efficiency, reliability, and having a compact layout. Requiring constant maintenance and the noise produced while in operation are some of the notable disadvantages.
The present invention is related to the gear system used in zero turn riding (ZTR) mowers and other comparable mobile equipment. The ZTR mower functions such that if one wheel turns more rapidly than the other, the machine moves along a curved path. If both wheels turn at the same speed, the machine follows a straight path. If one wheel turns and the other stops, or if the wheels turn in opposite directions, the mower pivots. However, when a single wheel spins, the turf the mower is used on is damaged. Furthermore, with the current controlling mechanism, turning and handling the ZTR mower on side hills and wet grass can be unfavorable.
The objective of the present invention is to address the aforementioned issues. More specifically, the present invention introduces a gear assembly that receives two inputs and also has two outputs. In particular, the present invention has a propelling input and a steering input. The propelling input spins both wheels in the same direction at the same speed. If the input speed is increased, the wheels are spun at a higher speed. If the direction is reversed, the direction of the wheels is reversed. The steering input of the present invention turns one wheel forward and the other wheel backwards. The wheels turn at the same speed in opposite directions. The steering input of the present invention allows the mower to be directed either left or right. Most importantly, the inputs are additive. As an example if the propelling input is simultaneously used with the steering input, one wheel will slow down and the other wheel will speed up. The output speeds are totally defined by the input speeds.
With the use of the present invention in vehicles such as ZTR mowers, the damage caused to the turf can be significantly reduced. Furthermore, by utilizing the present invention on a mobile vehicle, the ground traction between the wheels of the vehicle and the turf is better maintained. As a result, a user can control the mobile equipment on wet grass or on side hills much more effectively.